diff --git a/src/db/dbChannelIO.cpp b/src/db/dbChannelIO.cpp
index bd01f7e49..907b9d653 100644
--- a/src/db/dbChannelIO.cpp
+++ b/src/db/dbChannelIO.cpp
@@ -29,6 +29,7 @@
 #include "dbNotifyBlockerIL.h"
 
 tsFreeList < dbChannelIO > dbChannelIO::freeList;
+epicsMutex dbChannelIO::freeListMutex;
 
 dbChannelIO::dbChannelIO ( cacChannelNotify &notify, 
     const dbAddr &addrIn, dbServiceIO &serviceIO ) :
@@ -45,16 +46,16 @@ void dbChannelIO::initiateConnect ()
 
 dbChannelIO::~dbChannelIO ()
 {
-    this->lock ();
+    dbAutoScanLock ( *this->addr.precord );
 
     /*
      * remove any subscriptions attached to this channel
      */
-    tsDLIterBD <dbSubscriptionIO> iter = this->eventq.firstIter ();
+    tsDLIterBD < dbSubscriptionIO > iter = this->eventq.firstIter ();
     while ( iter.valid () ) {
         tsDLIterBD <dbSubscriptionIO> next = iter;
         next++;
-        iter->destroy ();
+        iter->cancel ();
         iter = next;
     }
 
@@ -65,8 +66,6 @@ dbChannelIO::~dbChannelIO ()
     if ( this->pGetCallbackCache ) {
         delete [] this->pGetCallbackCache;
     }
-
-    this->unlock ();
 }
 
 int dbChannelIO::read ( unsigned type, unsigned long count, void *pValue )
@@ -97,29 +96,29 @@ int dbChannelIO::read ( unsigned type, unsigned long count, cacNotify &notify )
         return ECA_BADCOUNT;
     }
 
-    this->lock ();
-    if ( this->getCallbackCacheSize < size) {
-        if ( this->pGetCallbackCache ) {
-            delete [] this->pGetCallbackCache;
+    {
+        dbAutoScanLock ( *this->addr.precord );
+        if ( this->getCallbackCacheSize < size) {
+            if ( this->pGetCallbackCache ) {
+                delete [] this->pGetCallbackCache;
+            }
+            this->pGetCallbackCache = new char [size];
+            if ( ! this->pGetCallbackCache ) {
+                this->getCallbackCacheSize = 0ul;
+                return ECA_ALLOCMEM;
+            }
+            this->getCallbackCacheSize = size;
         }
-        this->pGetCallbackCache = new char [size];
-        if ( ! this->pGetCallbackCache ) {
-            this->getCallbackCacheSize = 0ul;
-            this->unlock ();
-            return ECA_ALLOCMEM;
+        int status = db_get_field ( &this->addr, static_cast <int> ( type ), 
+                        this->pGetCallbackCache, static_cast <int> ( count ), 0);
+        if ( status ) {
+            notify.exceptionNotify ( *this, ECA_GETFAIL, 
+                "db_get_field () completed unsuccessfuly" );
+        }
+        else { 
+            notify.completionNotify ( *this, type, count, this->pGetCallbackCache );
         }
-        this->getCallbackCacheSize = size;
     }
-    int status = db_get_field ( &this->addr, static_cast <int> ( type ), 
-                    this->pGetCallbackCache, static_cast <int> ( count ), 0);
-    if ( status ) {
-        notify.exceptionNotify ( *this, ECA_GETFAIL, 
-            "db_get_field () completed unsuccessfuly" );
-    }
-    else { 
-        notify.completionNotify ( *this, type, count, this->pGetCallbackCache );
-    }
-    this->unlock ();
     notify.release ();
     return ECA_NORMAL;
 }
@@ -147,15 +146,13 @@ int dbChannelIO::write ( unsigned type, unsigned long count,
     }
 
     if ( ! this->pBlocker ) {
-        this->lock ();
+        dbAutoScanLock ( *this->addr.precord );
         if ( ! this->pBlocker ) {
             this->pBlocker = new dbPutNotifyBlocker ( *this );
             if ( ! this->pBlocker ) {
-                this->unlock ();
                 return ECA_ALLOCMEM;
             }
         }
-        this->unlock ();
     }
 
     // must release the lock here so that this can block
@@ -179,22 +176,14 @@ int dbChannelIO::subscribe ( unsigned type, unsigned long count,
         pReturnIO = pIO;
     }
     else {
-        pIO->destroy ();
+        pIO->cancel ();
     }
     return status;
 }
 
-void dbChannelIO::lockOutstandingIO () const
-{
-}
-
-void dbChannelIO::unlockOutstandingIO () const
-{
-}
-
 void dbChannelIO::show ( unsigned level ) const
 {
-    this->lock ();
+    dbAutoScanLock ( *this->addr.precord );
     printf ("channel at %p attached to local database record %s\n", 
         static_cast <const void *> ( this ), this->addr.precord->name );
 
@@ -216,5 +205,4 @@ void dbChannelIO::show ( unsigned level ) const
             this->pBlocker->show ( level - 2u );
         }
     }
-    this->unlock ();
 }
diff --git a/src/db/dbChannelIOIL.h b/src/db/dbChannelIOIL.h
index d646688df..944af5b1e 100644
--- a/src/db/dbChannelIOIL.h
+++ b/src/db/dbChannelIOIL.h
@@ -34,11 +34,13 @@ inline void dbChannelIO::destroy ()
 
 inline void * dbChannelIO::operator new ( size_t size )
 {
+    epicsAutoMutex locker ( dbChannelIO::freeListMutex );
     return dbChannelIO::freeList.allocate ( size );
 }
 
 inline void dbChannelIO::operator delete ( void *pCadaver, size_t size )
 {
+    epicsAutoMutex locker ( dbChannelIO::freeListMutex );
     dbChannelIO::freeList.release ( pCadaver, size );
 }
 
@@ -58,16 +60,6 @@ inline void dbChannelIO::subscriptionUpdate ( unsigned type, unsigned long count
     this->serviceIO.subscriptionUpdate ( this->addr, type, count, pfl, notify );
 }
 
-inline void dbChannelIO::lock () const
-{
-    dbScanLock ( this->addr.precord );
-}
-
-inline void dbChannelIO::unlock () const
-{
-    dbScanUnlock ( this->addr.precord );
-}
-
 inline dbEventSubscription dbChannelIO::subscribe ( dbSubscriptionIO &subscr, unsigned mask )
 {
     return this->serviceIO.subscribe ( this->addr, subscr, mask );
diff --git a/src/db/dbNotifyBlockerIL.h b/src/db/dbNotifyBlockerIL.h
index af8a82d4c..e38dabdf8 100644
--- a/src/db/dbNotifyBlockerIL.h
+++ b/src/db/dbNotifyBlockerIL.h
@@ -15,16 +15,6 @@
  *	505 665 1831
  */
 
-inline void dbPutNotifyBlocker::lock () const
-{
-    this->chan.lock ();
-}
-
-inline void dbPutNotifyBlocker::unlock () const
-{
-    this->chan.unlock ();
-}
-
 inline void dbPutNotifyBlocker::destroy ()
 {
     delete this;
@@ -32,10 +22,12 @@ inline void dbPutNotifyBlocker::destroy ()
 
 inline void * dbPutNotifyBlocker::operator new ( size_t size )
 {
+    epicsAutoMutex locker ( dbPutNotifyBlocker::freeListMutex );
     return dbPutNotifyBlocker::freeList.allocate ( size );
 }
 
 inline void dbPutNotifyBlocker::operator delete ( void *pCadaver, size_t size )
 {
+    epicsAutoMutex locker ( dbPutNotifyBlocker::freeListMutex );
     dbPutNotifyBlocker::freeList.release ( pCadaver, size );
 }
diff --git a/src/db/dbPutNotifyBlocker.cpp b/src/db/dbPutNotifyBlocker.cpp
index d735c3e40..2538a23fb 100644
--- a/src/db/dbPutNotifyBlocker.cpp
+++ b/src/db/dbPutNotifyBlocker.cpp
@@ -37,6 +37,7 @@
 #define S_db_Pending 	(M_dbAccess|37)
 
 tsFreeList <dbPutNotifyBlocker> dbPutNotifyBlocker::freeList;
+epicsMutex dbPutNotifyBlocker::freeListMutex;
 
 dbPutNotifyBlocker::dbPutNotifyBlocker ( dbChannelIO &chanIn ) :
     pPN (0), chan ( chanIn )
@@ -45,18 +46,16 @@ dbPutNotifyBlocker::dbPutNotifyBlocker ( dbChannelIO &chanIn ) :
 
 dbPutNotifyBlocker::~dbPutNotifyBlocker ()
 {
-    this->lock ();
+    dbAutoScanLockCA ( this->chan );
     if ( this->pPN ) {
-        this->pPN->destroy ();
+        this->pPN->cancel ();
     }
-    this->unlock ();
 }
 
 void dbPutNotifyBlocker::putNotifyDestroyNotify ()
 {
-    this->lock ();
+    dbAutoScanLockCA ( this->chan );
     this->pPN = 0;
-    this->unlock ();
 }
 
 dbChannelIO & dbPutNotifyBlocker::channel () const
@@ -73,38 +72,38 @@ int dbPutNotifyBlocker::initiatePutNotify ( cacNotify &notify,
         return ECA_ALLOCMEM;
     }
 
-    // wait for current put notify to complete
-    this->lock ();
-    if ( this->pPN ) {
-        epicsTime begin = epicsTime::getCurrent ();
-        do {
-            this->unlock ();
-            this->block.wait ( 1.0 );
-            if ( epicsTime::getCurrent () - begin > 30.0 ) {
-                pIO->destroy ();
-                return ECA_PUTCBINPROG;
+    while ( true ) {
+        {
+            dbAutoScanLockCA ( this->chan );
+            if ( ! this->pPN ) {
+                this->pPN = pIO;
+                int status = this->pPN->initiate ( addr, type, count, pValue );
+                if ( status != ECA_NORMAL ) {
+                    pIO->cancel ();
+                    this->pPN = 0;
+                }
+                return status;
             }
-            this->lock ();
-        } while ( this->pPN );
+        }
+        // wait for put notify in progress to complete
+        this->block.wait ( 1.0 );
+        epicsTime begin = epicsTime::getCurrent ();
+        if ( epicsTime::getCurrent () - begin > 30.0 ) {
+            pIO->cancel ();
+            return ECA_PUTCBINPROG;
+        }
     }
-    this->pPN = pIO;
-    int status = this->pPN->initiate ( addr, type, count, pValue );
-    if ( status != ECA_NORMAL ) {
-        this->pPN->destroy ();
-        this->pPN = 0;
-    }
-    this->unlock ();
-    return status;
 }
 
 extern "C" void putNotifyCompletion ( putNotify *ppn )
 {
     dbPutNotifyBlocker *pBlocker = static_cast < dbPutNotifyBlocker * > ( ppn->usrPvt );
-    pBlocker->lock ();
-    pBlocker->pPN->completion ();
-    pBlocker->pPN->destroy ();
-    pBlocker->pPN = 0;
-    pBlocker->unlock ();
+    {
+        dbAutoScanLockCA ( pBlocker->chan );
+        pBlocker->pPN->completion ();
+        pBlocker->pPN->cancel ();
+        pBlocker->pPN = 0;
+    }
     pBlocker->block.signal ();
 }